Titanium-Nitride Removal

ABSTRACT

A chemical solution that removes undesired metal hard mask yet remains selective to the device wiring metallurgy and dielectric materials. The present invention decreases aspect ratio by selective removal of the metal hard mask before the metallization of the receiving structures without adverse damage to any existing metal or dielectric materials required to define the semiconductor device, e.g. copper metallurgy or device dielectric. Thus, an improved aspect ratio for metal fill without introducing any excessive trapezoidal cross-sectional character to the defined metal receiving structures of the device will result.

CROSS REFERENCE TO RELATED APPLICATION

This application is a divisional of U.S. patent application Ser. No.13/343,190, filed Jan. 4, 2012, the entire content and disclosure ofwhich is incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to removal of metal hard mask materialsfor microelectronic devices. More particularly, the present inventionrelates to a chemical solution for removing metal hard mask selective todevice wiring and dielectric materials.

DESCRIPTION OF THE RELATED ART

Interconnect circuitry in semiconductor circuits consists of conductivemetallic circuitry surrounded by insulating dielectric material.Silicate glass vapor deposited from tetraethylorthosilicate (TEOS) waswidely used as the dielectric material, while alloys of aluminum wereused for metallic interconnects.

Demand for higher processing speeds has led to smaller sizing of circuitelements, along with the replacement of TEOS and aluminum alloys byhigher performance materials. Aluminum alloys have been replaced bycopper or copper alloys due to the higher conductivity of copper. TEOSand fluorinated silicate glass (FSG) have been replaced by the so calledlow-k dielectrics, including low-polarity materials such as organicpolymers, hybrid organic, inorganic materials, organosilicate glass(OSG), and carbon-doped oxide (CDO) glass. The incorporation ofporosity, i.e. air-filled pores, in these materials further lowers thedielectric constant of the material.

During dual-damascene processing of integrated circuits,photolithography is used to image a pattern on a device wafer.Photolithography techniques comprise the steps of coating, exposure anddevelopment. A wafer is coated with a positive or negative photoresistsubstance and subsequently covered with a mask that defines patterns tobe retained or removed in subsequent processes. Following the properpositioning of the mask, the mask has directed there through a beam ofmonochromatic radiation, such as ultraviolet (UV) light or deep UV (DUV)light (˜250 nm or 193 nm), to make the exposed photoresist material moreor less soluble in a selected rinsing solution. The soluble photoresistmaterial is then removed, or “developed,” thereby leaving behind apattern identical to the mask.

Thereafter, gas-phase plasma etching is used to transfer the patterns ofthe developed photoresist coating to the underlying layers, which mayinclude hard mask, inter-level dielectric (ILD), and/or etch stoplayers. Post-plasma etch residues are typically deposited onback-end-of-the-line (BEOL) structures and if not removed, may interferewith subsequent silicidation, proper metallization or contact formation.Post-plasma etch residues typically include chemical elements present onthe substrate and in the plasma gases. For example, if a TiN hard maskis employed, e.g. as a metal hard mask over a dielectric hard mask or asa layer over ILD, the post-plasma etch residues includetitanium-containing species, which are difficult to remove usingconventional wet cleaning chemistries.

In addition to the need to remove post-plasma residues, it is oftendesirable to remove or partially etch back the metal hard mask such as atitanium-containing hard mask and/or titanium-containing post plasmaetch residue, additional materials that are deposited during thepost-plasma etch process such as polymeric residues on the sidewalls ofthe patterned device and copper-containing residues in the open viastructures of the device are also preferably removed. No single wetcleaning composition has successfully removed all of residue and/or hardmask material while simultaneously being compatible with the ILD, otherlow-k dielectric materials, and metal interconnect materials.Compositions in the art claim to act in such a manner but are extremelyless effective than the claims indicate.

The integration of new materials, such as low-k dielectrics, intomicroelectronic devices places new demands on cleaning performance. Atthe same time, shrinking device dimensions reduces the tolerance forchanges in critical dimensions and damage to device elements. Etchingconditions can be modified in order to meet the demands of the newmaterials Likewise, post-plasma etch cleaning compositions must bemodified. Importantly, the cleaner should not damage the underlyingdielectric material or corrode metallic interconnect materials, e.g.sensitive ILD materials such as carbon-doped oxides and metal structuressuch as copper, tungsten, cobalt, aluminum, ruthenium and silicidesthereof, on the device.

Typical trench first metal hard mask integration removes the metal hardmask during the chemical mechanical polish process that removes excessdevice metallurgy. As integration tolerances tighten, the limitedability to correctly fill the defined metal receiving structures hasbeen clearly demonstrated.

Additional complications arise when a self-aligned via (SAV) processthat requires enhanced metal hard mask stability is used to provideadditional lithographic process window. While it may be beneficial formetal fill to add trapezoidal cross-sectional character to anintegration structure, line to line integration space can suffer if anexcessive trapezoidal cross-sectional design is used to enhance metalfill of very high aspect structures. A metal hard mask can be designedsuch that the lithographic transfer into the metal hard mask will definethe desired future trench structure and yet be resistant to undesireddamage during reactive ion etch transfer operations into the ILDstructures such that a metal fill definition structure may beconstructed without significant trapezoidal character. An unfortunatebyproduct of this aforementioned process is an increase in aspect ratio,which may further impede proper metallization.

What is needed to advance new technologies is a method to improve theaspect ratio for metal deposition while still maintaining the desiredline to line integration spaces. U.S. Pat. No. 7,922,824 suggests theuse of quaternary ammonium salts and quaternary ammonium alkali as partof a chemical composition for removing metal hard masks and post-plasmaetch residues. However, it teaches away from the use of quaternaryammonium salts and quaternary ammonium alkali without the addition of anacid modifying agent, such as citric acid, and by this teaching as wellas the direct omission of quaternary ammonium salts in the list ofoxidizing agent stabilizers indicates that quaternary ammonium salts andquaternary ammonium alkali cannot be used alone.

SUMMARY OF THE INVENTION

The present invention is a chemical solution that removes undesiredmetal hard mask yet remains selective to the device wiring metallurgyand dielectric materials. The present invention decreases aspect ratioby removal of the metal hard mask before the metallization of thereceiving structures without adverse damage to any existing metal ordielectric materials required to define the semiconductor device, e.g.copper metallurgy or device dielectric.

According to an embodiment of the present invention, a chemicalcomposition for removing a metal hard mask and etching residues from amicroelectronic device is provided. The chemical composition includes:an oxidizing agent selected from a group comprised of peroxides andoxidants which do not leave a residue or adversely attack copper; a pHcontrolling agent selected from a group comprised of quaternary ammoniumsalts and quaternary ammonium alkali; and an aqueous solution.

According to a further embodiment of the present invention, a method ofremoving a metal hard mask and etching residues from a microelectronicdevice is provided. The method includes steps of: etching a trench in aninterconnect structure selective to a dielectric capping layer by areactive ion etching process (RIE); applying a wet chemical compositionfor removing at least a portion of layers on the interconnect structureselective to the dielectric capping layer, said chemical compositioncomprising an oxidizing agent selected from a group comprised ofperoxides and oxidants which do not leave a residue or adversely attackcopper, a pH controlling agent selected from a group comprised ofquaternary ammonium salts and quaternary ammonium alkali and an aqueoussolution, wherein the composition has a pH in the range of about 7 toabout 14; and etching the interconnect structure to open the dielectriccapping layer above a copper device layer for filling the trench.

According to another embodiment of the present invention, a method ofremoving a metal hard mask and etching residues from a microelectronicdevice is provided. The method includes steps of: etching a trench in aninterconnect structure selective to a copper device layer by a reactiveion etching process (RIE); and applying a wet chemical composition forremoving at least a portion of layers on the interconnect structureselective to the copper device layer, said chemical compositioncomprising an oxidizing agent selected from a group comprised ofperoxides and oxidants which do not leave a residue or attack copper, apH controlling agent selected from a group comprised of quaternaryammonium salts and quaternary ammonium alkali and an aqueous solution,wherein the composition has a pH in the range of about 7 to about 14.

BRIEF DESCRIPTION OF THE DRAWINGS

The features and elements of the present invention are set forth withrespect to the appended claims and illustrated in the drawings.

FIG. 1 illustrates a microelectronic device prior to imaging andetching.

FIG. 2 illustrates the microelectronic device with an imagedlithographic stack.

FIG. 3 illustrates the microelectronic device after removal of thelithographic stack and etched metal hard mask.

FIG. 4A illustrates the microelectronic device post reactive ion etchselective to the dielectric cap (partial RIE) with etch residueaccording to the present invention.

FIG. 4B illustrates the microelectronic device post reactive ion etchselective to the dielectric cap (partial RIE) without etch residueaccording to the present invention.

FIG. 4C illustrates the partially etched microelectronic device after afull wet strip of the metal hard mask and etch residue according to thepresent invention.

FIG. 4D illustrates the partially etched microelectronic device after apartial wet strip of the metal hard mask and etch residue according tothe present invention.

FIG. 4E illustrates the partially etched microelectronic device postfinal reactive ion etch chamfer and clean according to the presentinvention.

FIG. 5A illustrates the microelectronic device post reactive ion etchselective to the copper line (full RIE) with etch residue.

FIG. 5B illustrates the microelectronic device post reactive ion etchselective to the copper line (full RIE) without etch residue.

FIG. 5C illustrates the fully etched microelectronic device after a fullwet strip of the metal hard mask and etch residue according to thepresent invention.

FIG. 5D illustrates the fully etched microelectronic device after apartial wet strip of the metal hard mask and etch residue according tothe present invention.

FIG. 5E illustrates the fully etched microelectronic device post finalreactive ion etch chamfer and clean according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following describes embodiments of the present invention withreference to the drawings. The embodiments are illustrations of theinvention, which can be embodied in various forms. The present inventionis not limited to the embodiments described below, rather representativefor teaching one skilled in the art how to make and use it. Some aspectsof the drawings repeat from one drawing to the next. The aspects retaintheir same numbering from their first appearance throughout each of thepreceding drawings.

The present invention is a chemical solution that removes undesiredmetal hard mask yet remains selective to the device wiring metallurgyand dielectric materials. The present invention decreases aspect ratioby selective removal of the metal hard mask before the metallization ofthe receiving structures without adverse damage to any existing metal ordielectric materials required to define the semiconductor device, e.g.copper metallurgy or device dielectric. Thus, an improved aspect ratiofor metal fill without introducing any excessive trapezoidalcross-sectional character to the defined metal receiving structures ofthe device will result.

Compositions of the invention may be embodied in a wide variety ofspecific formulations, as hereinafter more fully described. In all suchcompositions, wherein specific components of the composition arediscussed in reference to weight percentage ranges including a zerolower limit, it will be understood that such components may be presentor absent in various specific embodiments of the composition, and thatin instances where such components are present, they may be present atconcentrations as low as 0.0001 weight percent, based on the totalweight of the composition in which such components are employed.

The compositions of the invention may be formulated to substantiallyremove the titanium-containing residue, the polymeric sidewall resideand/or the copper-containing residue from the surface of themicroelectronic device without substantially damaging the underlyinginter level dielectric, metal interconnect materials and any dielectrichard mask, if present. The composition may be formulated to remove themetal hard mask layer from the surface of the microelectronic devicewithout substantially damaging the underlying low-k dielectric and metalinterconnect materials.

The chemical composition of the present invention includes an oxidizingagent and a pH controlling agent in an aqueous solution. De-ionizedwater is the principle solvent in the aqueous solution. The solvent mustbe at least free of any detrimental ions or other materials that couldinterfere with the cleaning action of the chemical composition ordegrade the cleanliness or future performance of the semiconductorcircuit. While de-ionized water is the most preferred solvent for thechemical composition, it is understood that other solvent systems withsimilar salvation properties to de-ionized water may also act as apossible solvent for the present invention. Thus, an aqueous solution ismost preferred. However, it is understood that other solvent systemssimilar to water may also act suitably for the present invention. Forexample, a 25% isopropanol, 75% de-ionized water solvent system may alsoproduce satisfactory results.

The oxidizing agent is preferably a peroxide, for example hydrogenperoxide and organic peroxides such as benzoyl peroxide. However,oxidizing agents may also include a non-metal with the ability tooxidize titanium nitride (TiN) to a soluble compound without leaving ametallic residue and oxidants that do not leave a residue or adverselyattack copper (Cu). It is very important that the oxidant/oxidizingagent, when dissolved in the chemical process, does not attack copper(Cu). For example, an oxidant may have an activity against copper whenused without the modifying agents in the present chemical composition.However, when so mixed with the other agents of the present chemicalcomposition, the activity of the oxidant is modified such that copper isnot detrimentally attacked. More specifically, the pH may be adjustedsuch that copper oxidation is minimized, and/or a surface adsorptionaction may occur due to agents in the present invention such that thecopper is protected from oxidation. The tetraethylammonium (TEA) ion mayact as a passavating adsorbent on a copper surface at the pH value ofthe present chemical composition as it is so designed.

The pH stabilizer adjusts the pH level in the chemical composition to arange of about 7 to about 14. Preferably, the pH stabilizer adjusts thepH level to a range of about 9 to about 10. Quaternary ammonium saltsand quaternary ammonium alkalis are preferred for use as a pH stabilizerin the present invention. Tetramethylammonium hydroxide (TMAH) is thequaternary ammonium that is primarily used in the industry. However,TMAH is toxic; it causes severe and typically unexpected health problemsfrom exposure. Unlike typical strong bases where an unprotected acuteexposure generally results in a caustic burn, TMAH may also introduce acomplication of decreased respiratory function. Thus, a quaternaryammonium that does not cause unexpected health side effects ispreferable. Tetraethylammonium hydroxide (TEAH) is the most preferred pHstabilizer in the present invention. In addition to the ability toadjust pH without the introduction of extraneous undesirable metal ions,such as alkaline earth or alkali metal ions, the TEA ion may also act asa passavating adsorbent on a copper surface at the pH value of thepresent chemical composition as it is also designed.

Regardless of whether the passavation action by TEA ions occur, theability to adjust pH without the introduction of extraneous undesirablemetal ions and the decreased hazard of TEAH makes TEAH the mostpreferred pH stabilizer for the present invention. It is understood thatother quaternary ammonium salts may also act as pH stabilizing agentswithout the additional passavation action towards a copper surface aslong as the resultant solution does not have detrimental activitytowards a copper surface; such a resultant solution is within thepurview of the present invention.

The approximate bath life of the chemical composition is in the range ofabout 18 hrs to about 22 hrs. When the chemical bath drops below 10-15%fresh bath, the bath is no longer useful. It is understood that typicalmethods used to extend solution bath life such as replenishment of theconsumed oxidizer in a recirculated solution may be used to extendusable bath life. Additionally, it is known that trace contaminationsuch as minute amounts of some metal ions may also dramatically decreasebath life. As such, the chemical composition of the present inventionmay be of single use (i.e., dispensed on the wafer for cleaning and sentto drain) or multiple use (i.e., reclaimed after initial processing useand stored for additional use). It is recognized that reclamation maydecrease the usable life of a reclaimed chemical bath. The use of asequestering agent (oxidant stabilizer) in the chemical bath canincrease the life of the bath during reclamation process use. Asequestering agent may be added to an un-reclaimed chemical composition;this sequestering agent may extend the usable bath life of such acomposition beyond that of a solution without the sequestering agent.Through the use of a sequestering agent, the oxidizer concentration maybe controlled such that excessive oxidant concentration addition to thechemical composition of the present invention is not necessary tocompensate for oxidant consumption by undesired decomposition due tocontamination, rather than by the normal consumption that occurs duringthe desired cleaning action of the present chemical composition.Thereby, the sequestering agent optimizes the concentration to furtherminimize the chemical composition's attack on the copper device layer byenabling a minimization of required oxidizer concentration in thepresent chemical composition.

Sequestering agents that can be used in the present invention are aminesand amino acids. The preferred sequestering agents are1,2-cyclohexanediamine-N,N,N′,N′-tetraacetic acid (CDTA),ethyenediaminetetraacetic acid (EDTA) and diethylenetriaaminopentaaceticacid (DTPA). The preferential use of complex sequestering agents, suchas CDTA, versus a simple sequestering agent, such as EDTA, is based onthe possibility of degradation of a simple sequestering agent over timeand at extended exposure to certain temperatures. However, it isunderstood that for some methods of application a simple sequesteringagent such as EDTA may be suitable. For example, a single use systemwhere heating occurs just before the solution dispenses on a wafer forchemical cleaning.

For further copper protection, a copper protectant can be added to thechemical composition. The preferred copper protectants for the presentinvention are hetero-organic inhibitors such as azoles. Preferably, atleast one of benzotriazole, 1,2,3 triazole, 1,3,4 triazole, 1,2,4triazole and imidazole are used in the chemical composition. The use ofhetero-organic inhibitors as opposed to simple organic compounds isbased on the possibility of degradation of organic compounds over timeand at extended exposure to certain temperatures. Azoles are organiccompounds containing nitrogen atoms with free electron pairs that arepotential sites for bonding with copper and that enable inhibitingaction. Also, there is a possibility of introduction of otherheteroatoms and groups in molecules of these compounds so there is awide range of derivatives that exhibit good inhibition characteristics.For example, it is understood that thiols produce active protection oncopper surfaces.

Preferred formulations for the chemical composition are:

-   1. 9% per wt oxidizing agent, 0.8% per wt pH stabilizer, 90.2%    aqueous solution;-   2. 9% per wt oxidizing agent, 0.8% per wt pH stabilizer, 10 ppm    sequestering agent, remainder aqueous solution;-   3. 9% per wt oxidizing agent, 0.8% per wt pH stabilizer, 10 ppm    sequestering agent, 100 ppm copper protectant, remainder aqueous    solution.

The preferred formulation of the chemical composition is hydrogenperoxide and TEAH in an aqueous solution, wherein the composition has apH in the range of about 9 to about 10. The chemical composition isdesigned to remove at least some titanium nitride (TiN). However, thechemical composition is also intended to remove at least some etchingresidues.

Accordingly, it is intended to be a full clean. It is understood that insome cases a full clean by a single solution may be too aggressive and asequential clean using multiple chemical systems may be less aggressivewith respect to copper or sensitive ILD structures. Performing a fullclean with a single solution is not to be done at the expense of thecopper device layer or sensitive ILD structures.

The chemical composition can be applied to a microelectronic device inmultiple ways. Referring now to FIG. 1, the microelectronic device mayinclude protective layers including a lithographic stack layer 160, ametal hard mask layer 150, such as titanium nitride, a dielectric hardmask layer 140, such as tetraethyl orthosilicate (TEOS), an inter-leveldielectric 130, and a dielectric capping layer 120, such as NBlock,above a copper device layer (copper line) 110 and another inter-leveldielectric 115. Prior to application of the chemical composition, thelithographic stack layer 160 is imaged, as shown in FIG. 2, creating anopening in the lithographic stack layer 160 exposing a portion of themetal hard mask 150. In FIG. 3, the lithographic stack layer 160 isremoved during etch of metal hard mask layer 150. The metal hard masklayer 150 is etched in such a way as to create an opening thus exposinga portion of the dielectric hard mask layer 140. Another etch isperformed for forming a trench in the microelectronic device. Theetching processes are most likely a reactive ion etching. The etchingprocess often leaves a residue on the microelectronic device and theprotective layers, as well as leaving a portion of the protection layersintact.

In one embodiment of the present invention, the etching process formsthe trench down to the dielectric capping layer 120, as shown in FIGS.4A-4D. This is called a partial etch. The dielectric capping layer 120is left in this embodiment of the present invention as a barrier for thecopper device layer to protect against the wet etching process, that is,application of the chemical composition of the present invention. FIG.4A shows the microelectronic device after a partial etch with residualetch residue 170. FIG. 4B shows the microelectronic device after apartial etch without the residual etch residue for clarity. Likewise,the residue is removed from FIGS. 4C-4E for clarity.

FIG. 4C shows the microelectronic device after a full wet etch process,that is, after application of the chemical composition of the presentinvention removing the entire metal hard mask layer 150. The chemicalcomposition is applied to the microelectronic device at a temperature inthe range of about 25° C. to about 80° C. Preferably, the chemicalcomposition is applied at about 60° C. For total removal, the chemicalcomposition is applied to the microelectronic device for about 1 minuteto about 5 minutes.

It has been observed that there is a pattern density relationship to thewet removal of metal hard masks such as titanium nitride (TiN). This isnot surprising based both on the incoming variation induced by priorreactive ion etch operations as well as possible chemical kineticrelationships. It is noted that in dense areas of the microelectronicdevice, an application of the chemical composition of the presentinvention for about 2 minutes is sufficient to achieve total removal ofa titanium nitride (TiN) metal hard mask with a deposited thickness ofabout 300 A to about 400 A. Whereas, in blanket areas of themicroelectronic device, the chemical composition is applied for about 4minutes to achieve total removal. Total removal would remove all layersabove the dielectric hard mask or inter-level dielectric layer if nodielectric hard mask layer is present.

A partial wet etch process can be performed as opposed to a total wetetch process as shown in FIG. 4D. A partial wet etch would clean andtaper at least a part of the microelectronic device for futuremetallization of the device, which would help the aspect ratio of thedevice and as such improve metallization. In FIG. 4D, a portion of themetal hard mask layer 150 is removed after the partial wet etch processexposing a portion of dielectric hard mask 140. This helps to mitigateany potential damage to the copper device layer 110. In order to performa partial etch, the chemical composition is applied for about 1 minuteto about 2 minutes at about 60° C. The wet etch, whether total orpartial, is followed by an etching process to open the dielectriccapping layer 120 and perform any additional tapering/hard maskchamfering necessary as shown in FIG. 4E. A cleaning process may also beperformed after the etching process to remove any additional residuesfrom the etching process.

FIGS. 5A-5E show another embodiment of the present invention where thetrench etching process forms the trench down to the copper device layer110. FIG. 5A shows the microelectronic device after a full etch withresidual etch residue 170. FIG. 5B shows the microelectronic deviceafter a full etch without the residual etch residue for clarity.Likewise, the residue is removed from FIGS. 5C-5E for clarity.

FIG. 5C shows the microelectronic device after a full wet etch process,that is, after application of the chemical composition of the presentinvention removing the entire metal hard mask 150. The chemicalcomposition is applied to the microelectronic device at a temperature inthe range of about 25° C. to about 80° C. Preferably, the chemicalcomposition is applied at about 60° C. For total removal, the chemicalcomposition is applied to the microelectronic device for about 1 minuteto about 5 minutes. Total removal would remove the entire metal hardmask layer above the dielectric hard mask or inter-level dielectriclayer if no dielectric hard mask layer is present.

It has been observed that there is a pattern density relationship to thewet removal of metal hard masks such as titanium nitride (TiN). This isnot surprising based both on the incoming variation induced by priorreactive ion etch operations as well as possible chemical kineticrelationships. It is noted that in dense areas of the microelectronicdevice, an application of the chemical composition of the presentinvention for about 2 minutes is sufficient to achieve total removal ofa titanium nitride (TiN) metal hard mask with a deposited thickness ofabout 300 A to about 400 A. Whereas, in blanket areas of themicroelectronic device, the chemical composition is applied for about 4minutes to achieve total removal. Total removal would remove all layersabove the dielectric hard mask or inter-level dielectric layer if nodielectric hard mask layer is present. Partial removal would leave somemetal hard mask structures, but modify the structures by a partialremoval of the structures while preserving all layers below thedielectric hard mask such as the dielectric hard mask or inter-leveldielectric layers if no dielectric hard mask layer is present.

A partial wet etch process can be performed as opposed to a total wetetch process as shown in FIG. 5D. A partial wet etch would clean andtaper the microelectronic device, which would help the aspect ratio ofthe device. In FIG. 5D, a portion of the metal hard mask layer 150 isremoved after the partial wet etch process exposing a portion ofdielectric hard mask 140. This helps to mitigate any potential damage tothe copper device layer 110. In order to perform a partial etch thechemical composition is applied for about 1 minute to about 2 minutes atabout 60° C. The partial wet etch may be followed by an etching processto perform any additional tapering/hard mask chamfering necessary asshown in FIG. 5E. A cleaning process may also be performed after theetching process to remove any additional residues from the etchingprocess.

The chemical composition and its accompanying methods can be used for 64nm pitch copper single and dual damascene interconnects using pitchsplit double patterning scheme to enable sub 80 nm pitch patterning, forexample. After the trench pattern is formed, the trenches are to befilled with metal. The metallization process has become a challenge forrecent technology generations with narrow width trenches patterned inlow-k dielectric material with hard masks on top of the dielectric film.The trenches often have a high aspect ratio with undercut under the hardmask. To prevent metal fill defects, the metal hard mask can be removedusing the chemical composition of the present invention using one of themethods described herein. This will significantly improve the metal fillprocess.

Trapezoidal structures in FIGS. 4E and 5E are exaggerated to illustratepossible chamfering of a structure by selective design, not by the lackof degrees of freedom to time a desired sidewall angle. A sidewall angleapproximating 90 degrees to the copper plane may be constructed usingthe present invention. However, the present invention enables theconstruction of a trapezoidal cross-section, if such a structure isdesired. A main difference is that this construction of a trapezoidalcross-section is by conscious design, rather than by an uncontrolledprocess side effect.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the invention. Asused herein, the singular forms “a”, “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises”and/or “comprising,” when used in this specification, specify thepresence of stated features, integers, steps, operations, elements,and/or components, but do not preclude the presence or addition of oneor more other features, integers, steps, operations, elements,components, and/or groups thereof.

The corresponding structures, materials, acts, and equivalents of allmeans or step plus function elements in the claims below are intended toinclude any structure, material, or act for performing the function incombination with other claimed elements as specifically claimed. It iswell known that different deposition conditions may result in metalfilms such as titanium nitride (TiN) hard mask films with differentproperties. Accordingly, the chemical ratios and/or contact times may beadjusted to produce similar results with varying titanium nitride (TiN)or other metal hard mask films. Thus, the description of the presentinvention has been presented for purposes of illustration anddescription, but is not intended to be exhaustive or limited to theinvention in the form disclosed.

The description of the present invention has been presented for purposesof illustration and description, but is not intended to be exhaustive orlimited to the invention in the form disclosed. Many modifications andvariations will be apparent to those of ordinary skill in the artwithout departing from the scope and spirit of the invention. Theembodiment was chosen and described in order to best explain theprinciples of the invention and the practical application, and to enableothers of ordinary skill in the art to understand the invention forvarious embodiments with various modifications as are suited to theparticular use contemplated.

What is claimed is:
 1. A chemical composition for removing a metal hardmask and etching residues from a microelectronic device, said chemicalcomposition comprising: an oxidizing agent selected from the groupconsisting of peroxides and oxidants which do not leave a residue and donot adversely attack copper; a pH controlling agent selected from thegroup consisting of a quaternary ammonium salt and a quaternary ammoniumalkali; and an aqueous solution.
 2. The chemical composition of claim 1,further comprising a sequestering agent selected from the groupconsisting of amines and amino acids.
 3. The chemical composition ofclaim 1, further comprising a copper protectant selected fromhetero-organic inhibitors.
 4. The chemical composition of claim 1,wherein said chemical composition has a pH from about 7 to about
 14. 5.The chemical composition of claim 1, wherein said chemical compositionhas a pH from about 9 to about
 10. 6. The chemical composition of claim1, wherein said oxidizing agent comprises hydrogen peroxide (H₂O₂),benzoyl peroxide (C₁₂H₁₀O₄) or a mixture thereof.
 7. The chemicalcomposition of claim 1, wherein the pH controlling agent istetraethylammonium hydroxide (TEAH).
 8. The chemical composition ofclaim 2, wherein the sequestering agent is at least one of1,2-cyclohexanediamine-N,N,N′,N′-tetraacetic acid (CDTA),ethyenediaminetetraacetic acid (EDTA) and diethylenetriaaminopentaaceticacid (DTPA).
 9. The chemical composition of claim 3, wherein the copperprotectant is at least one of benzotriazole, 1,2,3 triazole, 1,3,4triazole, 1,2,4 triazole and imidazole.
 10. The chemical composition ofclaim 1, wherein the aqueous solution comprises de-ionized water. 11.The chemical composition of claim 1, wherein said oxidizing agent ishydrogen peroxide (H₂O₂), said pH controlling agent istetraethylammonium hydroxide (TEAH) and said aqueous solution isde-ionized water, and wherein the chemical composition has a pH in therange of about 9 to about
 10. 12. The chemical composition of claim 1,wherein said aqueous solution comprises 25% isoproponal and 75%deionized water.
 13. The chemical composition of claim 1, wherein saidoxidizing agent is present in amount of 9% per weight, said pHcontrolling agent is present in an amount of 0.8%, and said aqueoussolution is present in an amount of 90.2%.
 14. The chemical compositionof claim 2, wherein said oxidizing agent is present in amount of 9% perweight, said pH controlling agent is present in an amount of 0.8%, saidsequestering agent is present in an amount of 10 ppm, and said remainderof said chemical composition, up to 100% per weight, is comprised ofsaid aqueous solution.
 15. The chemical composition of claim 3, whereinsaid oxidizing agent is present in an amount of 9% per weight, said pHcontrolling agent is present in an amount of 0.8%, said sequesteringagent is present in an amount of 10 ppm, said copper protectant ispresent in an amount of 100 ppm, and said remainder of said chemicalcomposition, up to 100% per weight, is comprised of said aqueoussolution.